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  1. #1321
    Moderator at Work ilan's Avatar
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    Milky Way could be catapulting stars into its outer halo
    Eleanor Imster in SPACE | May 3, 2020

    Scientists used computer simulations to learn that our Milky Way galaxy may sometimes launch newly forming stars into the space around itself – that is, into the halo of our galaxy – via outflows triggered by supernova explosions.


    An example of one of the movies from the FIRE-2 simulations

    Though mighty, the Milky Way and galaxies of similar mass are not without scars chronicling turbulent histories.

    So say scientists at the University of California, Irvine, who used the “hyper-realistic, cosmologically self-consistent” computer simulations generated via the FIRE-2 collaboration (FIRE stands for Feedback in Realistic Environments) to model our Milky Way galaxy’s rotation over time. In this way, they’ve learned that our galaxy may sometimes launch newly forming stars into the space around itself – that is, into the halo of our galaxy – via outflows triggered by supernova explosions.

    UC Irvine physicist Sijie Yu is lead author of this new study, which was published in March, 2020 in the peer-reviewed Monthly Notices of the Royal Astronomical Society. Yu said the findings were made possible partly by the availability of a powerful new set of computing tools. She said in a statement:

    The FIRE-2 simulations allow us to generate movies that make it seem as though you’re observing a real galaxy.

    They show us that as the galaxy center is rotating, a bubble driven by supernova[s] is developing, with stars forming at its edge. It looks as though the stars are being kicked out from the center.
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  2. #1322
    Moderator at Work ilan's Avatar
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    New closest-known black hole lies in a visible star system
    EarthSky Voices in SPACE | May 6, 2020

    Only 1,000 light-years away, the star system can be seen with the unaided eye.


    Artist’s concept of a black hole via ESO.
    A team of astronomers from the European Southern Observatory (ESO) and other institutes has discovered a black hole lying just 1,000 light-years from Earth. The black hole is closer to our solar system than any other found to date and forms part of a triple system that can be seen with the unaided eye. The team found evidence for the invisible object by tracking its two companion stars using the 2.2-meter telescope at ESO’s La Silla Observatory in Chile. They say this system could just be the tip of the iceberg, as many more similar black holes could be found in the future.

    Prior to this discovery, the closest-known black hole was A0620-00 in the constellation of Monoceros at a distance of 3,000 light years.

    Petr Hadrava of the Academy of Sciences of the Czech Republic in Prague, a co-author of the research, said:

    We were totally surprised when we realized that this is the first stellar system with a black hole that can be seen with the unaided eye.

    Located in the constellation of Telescopium, the system is so close to us that its stars can be viewed from the Southern Hemisphere on a dark, clear night without binoculars or a telescope.

    ESO scientist Thomas Rivinius, who led the study published May 6, 2020, in Astronomy & Astrophysics (doi: 10.1051/0004-6361/202038020), said:

    This system contains the nearest black hole to Earth that we know of.

    The team originally observed the system, called HR 6819, as part of a study of double-star systems. However, as they analyzed their observations, they were stunned when they revealed a third, previously undiscovered body in HR 6819: a black hole. The observations with the FEROS spectrograph on the 2.2-meter telescope at La Silla showed that one of the two visible stars orbits an unseen object every 40 days, while the second star is at a large distance from this inner pair.

    Dietrich Baade of ESO in Garching and co-author of the study, said:

    The observations needed to determine the period of 40 days had to be spread over several months …

    The hidden black hole in HR 6819 is one of the very first stellar-mass black holes found that do not interact violently with their environment and, therefore, appear truly black. But the team could spot its presence and calculate its mass by studying the orbit of the star in the inner pair. Rivinius, who is based in Chile, commented:

    An invisible object with a mass at least 4 times that of the sun can only be a black hole.

    Astronomers have spotted only a couple of dozen black holes in our galaxy to date, nearly all of which strongly interact with their environment and make their presence known by releasing powerful X-rays in this interaction. But scientists estimate that, over the Milky Way’s lifetime, many more stars collapsed into black holes as they ended their lives. The discovery of a silent, invisible black hole in HR 6819 provides clues about where the many hidden black holes in the Milky Way might be
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  3. #1323
    Moderator at Work ilan's Avatar
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    Why clouds form near black holes
    EarthSky Voices in SPACE | May 19, 2020

    Clouds in the greater universe are clumpy areas of greater density than their surroundings. Space telescopes have observed these cosmic clouds in the vicinity of supermassive black holes.


    This artist’s concept depicts a quasar, a type of active galactic nucleus, surrounded by a dusty donut shape (torus) and clumps called “clouds.” These clouds start small but can expand to be more than 1 parsec (3.3 light-years) wide. In this diagram, the clouds are at least 1 parsec from the torus. Image via Nima Abkenar/ NASA.
    Once you leave the majestic skies of Earth, the word cloud no longer means a white fluffy-looking structure that produces rain. Instead, clouds in the greater universe are clumpy areas of greater density than their surroundings.

    Space telescopes have observed these cosmic clouds in the vicinity of supermassive black holes, those mysterious dense objects from which no light can escape, with masses equivalent to more than 100,000 suns. There is a supermassive black hole in the center of nearly every galaxy, and it is called an active galactic nucleus (AGN) if it is gobbling up a lot of gas and dust from its surroundings. The brightest kind of AGN is called a quasar. While the black hole itself cannot be seen, its vicinity shines extremely brightly as matter gets torn apart close to its event horizon, its point of no return.

    But black holes aren’t truly like vacuum cleaners; they don’t just suck up everything that gets too close. While some material around a black hole will fall directly in, never to be seen again, some of the nearby gas will be flung outward, creating a shell that expands over thousands of years. That’s because the area near the event horizon – the threshold around a black hole where the escape velocity surpasses the speed of light – is extremely energetic; the high-energy radiation from fast-moving particles around the black hole can eject a significant amount of gas into the vastness of space.

    Scientists would expect that this outflow of gas would be smooth. Instead, it is clumpy, extending well beyond 1 parsec (3.3 light-years) from the black hole. Each cloud starts out small, but can expand to be more than 1 parsec wide – and could even cover the distance between Earth and the nearest star beyond the sun, Proxima Centauri.

    Astrophysicist Daniel Proga at the University of Nevada, Las Vegas, likens these clumps to groups of cars waiting at a highway onramp with stoplights designed to regulate the influx of new traffic. He said:

    Every now and then you have a bunch of cars.
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  4. #1324
    Moderator at Work ilan's Avatar
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    Astronomers find the Wolfe Disk, a galaxy that shouldn't exist, in the distant universe
    Ashley Strickland, CNN | Sat May 23, 2020


    Artists impression of the Wolfe Disk, a massive rotating disk galaxy in the early universe.
    (CNN) Astronomers have spotted a massive disk galaxy, not unlike our own, that formed 12.5 billion years ago when our 13.8 billion-year-old universe was only a tenth of its current age. But according to what scientists know about galaxy formation, this one has no business being in the distant universe.

    This discovery is challenging how astronomers think about galaxy formation in the early universe.
    It's known as Galaxy DLA0817g, but astronomers nicknamed it the Wolfe Disk after late astronomer Arthur M. Wolfe, former doctoral advisor to three of the study's four authors. It represents the most distant rotating disk galaxy they have ever observed, thanks to the Atacama Large Millimeter/submillimeter Array of telescopes in Chile known as ALMA.

    According to their observations, the galaxy's disk has a mass of 70 billion times that of our sun. It's also rotating at 170 miles per second, which is similar to our Milky Way galaxy. But galaxies with stable, well-formed disks, like the Milky Way, formed gradually and appeared later in the universe's timeline, with some dated to 6 billion years after the Big Bang.

    In the early days after the Big Bang, the universe was largely a blank slate. Eventually, this was followed by galaxy formation that was pretty messy. Small galaxies merged and crashed together along with hot gas clumps.

    "Most galaxies that we find early in the universe look like train wrecks because they underwent consistent and often 'violent' merging," said Marcel Neeleman, lead study author and postdoctoral researcher at the Max Planck Institute for Astronomy in Heidelberg, Germany, in a statement. "These hot mergers make it difficult to form well-ordered, cold rotating disks like we observe in our present universe."

    The study published this week in the journal Nature.

    So how did a well-formed rotating disk galaxy appear during this turbulent period? This galaxy formed and grew, researchers concluded, in a different way, known as cold-mode accretion.

    Much of what astronomers know about galaxy formation is based on hierarchy. In the beginning, halo-like structures of dark matter, a large, unseen component of the universe known by its effect on surrounding matter, drew in gas. Mergers created something larger where star formation was possible, and eventually, a galaxy was born.

    The gas drawn in by the dark matter halos was heated by the collisions, and it would form a disk once it cooled — which could take place over billions of years.

    Cold brew

    But in the cold scenario, much cooler gas is drawn into a new galaxy and allows for quicker formation of a disk.

    "We think the Wolfe Disk has grown primarily through the steady accretion of cold gas," said J. Xavier Prochaska, study coauthor and professor of astronomy and astrophysics of the University of California, Santa Cruz, in a statement. "Still, one of the questions that remains is how to assemble such a large gas mass while maintaining a relatively stable, rotating disk."

    The researchers also used data from the Hubble Space Telescope and the National Science Foundation's Karl G. Jansky Very Large Array of radio antennae in New Mexico to understand what kind of star formation was occurring in the galaxy.

    "The star formation rate in the Wolfe Disk is at least 10 times higher than in our own galaxy," explained Prochaska. "It must be one of the most productive disk galaxies in the early universe."

    Neeleman and his colleagues first spotted the Wolfe Disk using ALMA in 2017 when light from a quasar passed through hydrogen gas around the galaxy and revealed it. A quasar, which looks a bit like a star through a telescope, is actually a remote object that emits a large amount of energy likely powered by matter falling on a black hole at the center of a galaxy. The light helped them identify this normal galaxy, rather than the direct light emitted by extremely bright galaxies.

    Otherwise, distant galaxies are hard to observe because they're so faint. But this "absorption" of light method using quasars can happen when the telescopes, galaxy and quasar are in alignment, which is rare — unless galaxies like this were more common in the early universe.

    "The fact that we found the Wolfe Disk using this method, tells us that it belongs to the normal population of galaxies present at early times," Neeleman said. "When our newest observations with ALMA surprisingly showed that it is rotating, we realized that early rotating disk galaxies are not as rare as we thought and that there should be a lot more of them out there. Thanks to ALMA, we now have unambiguous evidence that they occur as early as 1.5 billion years after the Big Bang."

    Future research and observation is needed to understand how common this cold method of galaxy formation was in the early universe.
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  5. #1325
    Moderator at Work ilan's Avatar
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    ALMA spots the twinkling heart of our Milky Way
    EarthSky in SPACE | May 26, 2020

    Astronomers used the ALMA telescope in Chile to observe irregular flickers in millimeter-waves from the center of our Milky Way galaxy: the twinkling heart of the galaxy.Astronomers using the ALMA telescope in Chile’s Atacama Desert have now tracked quasi-periodic (irregular) flickers in millimeter-waves emanating from the center of our Milky Way galaxy.


    This image shows the flickering or twinkling heart of our Milky Way galaxy. These dots represent measurements of changes in the intensity of emission, at millimeter wavelengths, from the galaxy’s center. The changes were detected by the ALMA telescope in Chile. The colossal black hole at the galaxy’s center is called Sagittarius A* (pronounced Sagittarius A-Star).
    Astronomers using the ALMA telescope in Chile’s Atacama Desert have now tracked quasi-periodic (irregular) flickers in millimeter-waves emanating from the center of our Milky Way galaxy.

    They've interpreted the flickering as coming from spots of radio emission in a disk encircling the 4-million-solar-mass black hole at our Milky Way’s heart. The black hole is known as Sagittarius (Sgr) A* (pronounced Sagittarius A-Star). The radio spots appear to orbit the black hole closer than Mercury orbits our sun. Keio University graduate student Yuhei Iwata is lead author of the paper, published April 2, 2020, in the peer-reviewed Astrophysical Journal Letters. Iwata said in a May 22 statement from ALMA:

    It has been known that Sgr A* sometimes flares up in millimeter wavelength. This time, using ALMA, we obtained high-quality data of radio-wave intensity variation of Sgr A* for 10 days, 70 minutes per day. Then we found two trends: quasi-periodic variations with a typical time scale of 30 minutes and hour-long slow variations.

    The result is interesting not only because it’s a direct measurement of the flickering, or twinkling, radiation at the heart of the Milky Way, but also because, the astronomers believe, the observations are linked to the way space-time behaves in the extreme gravity environment surrounding a black hole.
    Last edited by ilan; 05-26-2020 at 12:22 PM.
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  6. #1326
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    SpaceX and Nasa are launching a Rocket today aren't they ?
    It is first launch on US soil since the last Shuttle launch.
    Dorothy Kilgallen / Malala Yousafzai
    Shoshana Zuboff / Aaron Swartz
    Noam Chomsky / Peter Schiff

  7. #1327
    Fire from Within dara's Avatar
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    Bummer on the abort today (weather). Next window is Saturday.

  8. #1328
    Super Modz crazed 8.4's Avatar
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    Quote Originally Posted by dara View Post
    Bummer on the abort today (weather). Next window is Saturday.
    I wanna know what ilan has on all this.
    These game changers in the area of space exploration are fantastic. Not that coperation with SpaceX and NASA are a game changer, but damn fine to see.

    I seen a model the other day about how things could go.
    Seeing future models of space stations and groups of such stations, each with their own functions and limits, like an aircraft carrier at sea.
    Dorothy Kilgallen / Malala Yousafzai
    Shoshana Zuboff / Aaron Swartz
    Noam Chomsky / Peter Schiff

  9. #1329
    Moderator at Work ilan's Avatar
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    We needed private enterprise to re-energize space exploration in the US. Too many people in government felt delegating money for space exploration was a waste. Unfortunately, people wanted to see an immediate return on investment, and the advancement of science wasn't viewed as a viable measure of success. I hope we have liftoff on Sat.
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  10. #1330
    Moderator at Work ilan's Avatar
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    1st quarter moon is May 29-30
    Deborah Byrd in MOON PHASES | May 27, 2020

    The 1st quarter moon happens on May 30, 2020, at 03:31 UTC. As viewed from anywhere on Earth, a 1st quarter moon is at its highest in the sky at sunset, looking like half a pie.


    Composite image of a moon nearly at 1st quarter with some of the features you can see on the moon at this phase – captured April 30, 2020 – by our friend Dr Ski in the Philippines. He wrote: “… 10 hours before 1st quarter and the Lunar V and Lunar X are well defined …” Thank you, Dr Ski!
    A first quarter moon rises around noon and sets around midnight. You’ll likely spot it in late afternoon or early evening, when it’s at its highest in the sky. At this moon phase, the moon is showing us precisely half of its lighted half. Or you might say that – at first quarter moon – we’re seeing half the moon’s day side.

    We call this moon a quarter and not a half because it is one quarter of the way around in its orbit of Earth, as measured from one new moon to the next. Also, although a first quarter moon appears half-lit to us, the illuminated portion we see of a first quarter moon truly is just a quarter. We’re now seeing half the moon’s day side, that is. Another lighted quarter of the moon shines just as brightly in the direction opposite Earth!

    Bottom line: The next 1st quarter moon will come on May 30, 2020, at 03:31 UTC. That’s May 29, 10:31 p.m. CDT.
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